How to use the @aws-cdk/cx-api.OUTDIR_ENV function in @aws-cdk/cx-api

Object.defineProperty(this, APP_SYMBOL, { value: true });

    this.loadContext(props.context);

    if (props.stackTraces === false) {
      this.node.setContext(cxapi.DISABLE_METADATA_STACK_TRACE, true);
    }

    if (props.runtimeInfo === false) {
      this.node.setContext(cxapi.DISABLE_VERSION_REPORTING, true);
    }

    // both are reverse logic
    this.runtimeInfo = this.node.tryGetContext(cxapi.DISABLE_VERSION_REPORTING) ? false : true;
    this.outdir = props.outdir || process.env[cxapi.OUTDIR_ENV];

    const autoSynth = props.autoSynth !== undefined ? props.autoSynth : cxapi.OUTDIR_ENV in process.env;
    if (autoSynth) {
      // synth() guarantuees it will only execute once, so a default of 'true'
      // doesn't bite manual calling of the function.
      process.once('beforeExit', () => this.synth());
    }

    if (props.treeMetadata === undefined || props.treeMetadata) {
      new TreeMetadata(this);
    }
  }

this.loadContext(props.context);

    if (props.stackTraces === false) {
      this.node.setContext(cxapi.DISABLE_METADATA_STACK_TRACE, true);
    }

    if (props.runtimeInfo === false) {
      this.node.setContext(cxapi.DISABLE_VERSION_REPORTING, true);
    }

    // both are reverse logic
    this.runtimeInfo = this.node.tryGetContext(cxapi.DISABLE_VERSION_REPORTING) ? false : true;
    this.outdir = props.outdir || process.env[cxapi.OUTDIR_ENV];

    const autoSynth = props.autoSynth !== undefined ? props.autoSynth : cxapi.OUTDIR_ENV in process.env;
    if (autoSynth) {
      // synth() guarantuees it will only execute once, so a default of 'true'
      // doesn't bite manual calling of the function.
      process.once('beforeExit', () => this.synth());
    }

    if (props.treeMetadata === undefined || props.treeMetadata) {
      new TreeMetadata(this);
    }
  }

// by pass "synth" if app points to a cloud assembly
  if (await fs.pathExists(app) && (await fs.stat(app)).isDirectory()) {
    debug('--app points to a cloud assembly, so we by pass synth');
    return new cxapi.CloudAssembly(app);
  }

  const commandLine = await guessExecutable(appToArray(app));

  const outdir = config.settings.get([ 'output' ]);
  if (!outdir) {
    throw new Error('unexpected: --output is required');
  }
  await fs.mkdirp(outdir);

  debug('outdir:', outdir);
  env[cxapi.OUTDIR_ENV] = outdir;

  // Send version information
  env[cxapi.CLI_ASM_VERSION_ENV] = cxapi.CLOUD_ASSEMBLY_VERSION;
  env[cxapi.CLI_VERSION_ENV] = versionNumber();

  debug('env:', env);

  await exec();

  return new cxapi.CloudAssembly(outdir);

  async function exec() {
    return new Promise((ok, fail) => {
      // We use a slightly lower-level interface to:
      //
      // - Pass arguments in an array instead of a string, to get around a